This invention relates to tobacco-smoke filter elements of smoking articles.
It is well known that after smoking articles have been smoked, the odor therefrom, in the absence of fresh air, remains in a room or ashtray for a considerable time. In enclosed spaces such as these the after-effects of smoking leave a lingering stale odor which can be found to be unpleasant by smokers and non-smokers.
This invention has as an object to overcome the odorous after-effects of smoking, particularly in enclosed spaces.
Various means of encapsulating liquid substances for release in tobacco-smoke filter elements have been proposed. For example, the Applicant has previously described in U.K. Patent Specification No. 1 234 802 the packaging of liquid substances in a hollow, preferably flexible, tube. The tube is filled with the substance in liquid form, then subjected to cooling to freeze the liquid substance, cut to lengths and then end-sealed by dipping into a solidifiable sealing medium or by application of end caps, for example.
U.K. 1 257 290 describes the use of such filled flexible tubes in a three-component filter element, a central section comprising the sealed capsule between two end sections. The filled flexible tubes are subjected to digital pressure before smoking occurs, whereby the friable end-sealant ruptures to release the encapsulated liquid and the released liquid may enhance the filtration efficiency of the filter element or otherwise affect the smoke flavour characteristics of the smoking article during smoking.
U.K. 1 267 272 discloses a method of producing wax coated capsules containing a liquid material such as water, which might also be useful in filter elements where increased filtration efficiency or flavour enhancement during smoking is desired.
However, all of these prior art patents are concerned with providing encapsulation methods which release the encapsulated material before smoking occurs. The capsules are designed to rupture under the digital pressures encountered before smoking.
This invention seeks to utilize an encapsulation technique which results in a filter element comprising a capsule which is resistant to compression from either digital or buccal pressure, yet which is fragile enough to break under pressure applied to the filter element after smoking ceases during the manual extinguishing process or xe2x80x98stubbing outxe2x80x99 thereof.